Hey all, thought I'd do a review on this mouse just for fun. Hope it is helpful to someone out there.
Let me start with the basics. I've used the M90 for about 3 months on a Razer Scarab mousepad. The games I have played most with this mouse are Battlefield 3, Tribes:Ascend, League of Legends, Starcraft 2, Torchlight and the Guild Wars 2 Beta. I've used several other "gaming mice" I can use for comparison. Most notably the logitech G5, logitech G500 and a Razer deathadder V1&V2. You can find my review of the G500 here.
Shape / Feel / Appearance
The Corsair M90 is relatively short mouse and almost a half an inch shorter than the G500. However, it is just as wide and has a relatively high "bump" at the back of the mouse where you rest your palm. Because of this shape, it seems most suitable for people that use a claw grip. This means that they have the back of the mouse touching their palm while having their fingers arched to operate the left and right mouse button. I have seen the palm grip being mentioned as a viable grip for this mouse, but for people with big or even regular sized hands I have to disagree that this is a viable grip. I have pretty large hands, and when I try to palm the mouse my middle finger extends far past the right mouse button and almost touches the mousepad. This is partly caused by the fact that the mouse is generally short, but made worse because Corsair has chosen to make the right mouse button shorter than the left mouse button. A strange choice, as usually the middle finger is longer then the index finger. Other mice that have an asymmetric design (Like the Roccat Kone for example) usually do things the other way around, with the right mouse button being the one that is longer. If your hands are sufficiently small however, you may be able to make the palm grip work since the rest of the mouse seems to facilitate the grip relatively well. It is also possible to use the fingertip grip with the mouse. However, you should take into account that the weight and the location of the buttons on the mouse are not ideal for this gripstyle.
My usual grip is somewhere in between palm and clawgrip, and I had to use a claw-grip and arch my fingers a bit more then usual for them to actually fit on the mouse. When I did, I found the shape of the mouse to be very comfortable. The shape of the large bump in the back fits nicely in my palm. The indentation on the left side is perfect for the thumb to rest in, which enables you to easily lift the mouse. On the right side of the mouse, where the pinky and ring finger rest, there is another indentation also making lifting the mouse easier.
The mouse has an aluminium uni-body design that adds quite a bit of weight to it but also gives it a really solid feel. Unlike most mice that I have tried over the last few years this mouse does not have that cheap plasticky feel, and feels good when holding it. The overall construction both looks and feels solid. Contributing to this is the rubberized coating that covers most of the mouse which feels nice and provides a good grip. On the left side where the buttons are, the the material used is a smooth plastic while the buttons themselves are a slightly rougher more grainy plastic. On the right side where the pinky and ring finger rest the material used is a rougher more textured plastic for added grip.
The mouse does not come with adjustable weight and is very heavy. It is heavier than the already heavy Logitech G500 (without weights) for example, which was up until now one of the heaviest mice I have ever used. Depending on playstyle and preference, some may find it already too heavy actually. I myself have gotten used to the weight, and since the last mouse I used was also very heavy the transition to this mouse was not such a big deal. But since I play on low sensitivity and pick up the mouse a lot, I do have to say that it is definitely noticeable and not everyone will like it.
Sidebuttons
The side-buttons are one of the major selling points of the M90 as it is marketed as an "MMO/RTS Mouse" due to the large number of buttons that are available. One thing i should note before I get into the use and feel of these buttons is that I have allowed myself to adjust and get used to them before the review. To familiarize myself with them they were used in games as keybinds, used for work as various macros, but also outside of games and work with functions like cut, copy, paste, find, forward and backward assigned to them.
I feel like the location of the side-buttons on the m90 are really hit or miss depending on the size of your hands and the grip you use to hold the mouse. You could argue that this is true for any mouse, but it holds especially true for the M90. With my relatively large hands in a claw grip where I have my entire thumb in the "thumb-groove" on the left side of the mouse, I found the locations of some of the side buttons uncomfortable, while others were easily in reach without having to bend my fingers into uncomfortable positions. In this regard the mouse is similar to my experience with other MMO mice with this many buttons.
The two buttons that are furthest back (closest to my palm) I find almost impossible to use in any high-pace game. The two buttons near the bottom (closest to the base plate of the mouse) are well within reach, but the problem here is that they are hard to push. You really need to apply quite a lot of force, and annoyingly, quite a lot of force under the correct angle to use them. Pushing them seems easiest by applying force horizontally from the side rather than vertically, which is odd since they seem designed to be pushed by moving the thumb downward from its resting position. Instead, they are far more easy to use by lifting the thumb and pressing them sideways.
With the exception of the most forward placed button (closest to the tip of the index finger), which required me to change the way I hold the mouse to use it, I found the remaining buttons on the side of the mouse actually quite comfortable to use. After I got used to them, I could use them without problem even in more fast paced games. For example in battlefield 3, melee, Gadget 1 and gadget 2 (for example, medkit and revive) were bound to some of these side buttons and worked well. I'm no pro, but hold a 500+ SPM and 1.8+ K/D ratio while playing objective based games on bigger maps. I say this to give an indication that I do actually require the mouse to work well, and while I just play for kicks, I play "seriously" enough for a button that does not work well to be a serious hindrance.
That said, I felt like the buttons still needed a little more force than what I would have liked to see. The design of the buttons looks as though you should push them with different parts of the thumb by sort of leaning your thumb into them. You can forget about using them like that. With the exception of the button in the upper-right corner, I ended up using the tip of my thumb to push all of the others. Since they are not all that easy to press, it is just easier to apply the required force this way. Using the buttons like this was actually fine as using them caused me no discomfort. The buttons do not really give a loud or satisfying audible or tactile feedback. Instead of feeling a clear "click" you feel and hear a more muffled click when you press them which is something you can get used to, but did not feel immediately very satisfying and reassuring.
One thing I like about the buttons is that they are quite large. They may not be incredibly easy to press but they are very easy to find. The raised ridge that is on the buttons helped in distinguishing them from each other. I also found their location on the mouse easy to remember. Another thing I did appreciate about the location of the buttons is that they do not interfere with anything when you are not using them. In the space where you would naturally rest your thumb there is an open space, allowing you to tightly grip the mouse without having to worry about the buttons. This is why I was a little surprised Corsair had chosen to make the buttons hard to press. It seems to me that having the open space for the thumb in the middle of all these buttons already takes care of the problem of accidental button presses.
All in all I thought the buttons on the side could use some improvement, but perform decently. Especially after I got used to it, I started using the buttons quickly, accurately and with confidence and stopped worrying about them being harder to push then what i am used to. With some experience and a little muscle memory you will be able to use them fine though they will never be as comfortable to me as some of the more clicky easier to use buttons found on some other mice. I do however feel like the shape size and location of the buttons compensates for this.
LMB+extra buttons / RMB
The left and right click on the mouse have a really low travel distance and require very little force to be used. When mice "click easily" it is easy for the clicking to end up feeling "loose" and unintentional, which is not the case here. I feel like the clicking here is solid. I enjoy how to combination of the weight of the mouse with the very light clicking enables me to click rapidly in FPS without going off target.
The buttons near the index finger are in a good location. I like that they have been moved as far forward as possible so that it is not necessary to arch your index finger a lot to press them. It should be noted that the software allows you to re-bind these buttons to any keypress on the keyboard, giving you the same freedom to use them as the thumb buttons. However, they require a lot of force to push and are hard to tell apart by touch, making them less than ideal to use in a game. I used them to switch between profiles that I had saved on the mouse. For this purpose they worked fine.
Scrollwheel
I really like the scroll wheel on the M90. I am quite picky with scroll wheels and it is one of the things I think Razer mice always get right. The wheel feels weighted and heavy. The scroll wheel also has a rubberized grip and is quite wide, which feels quite nice to the touch and contributes to the overall solid and grippy feel of the mouse. Clicking the wheel is easy and gives a satisfying feedback. The wheel does lie pretty deep in the mouse's body and does not stick out as much as the wheels found on some other mice. For me, this did not noticeably impact how hard or easy it was to use. It is one of the better scroll wheels I have used in mice and I like it as much as I liked the scroll-wheel on the deathadder, which is not entirely different in feel due to its width, the heavy scrolling, rubberized material and satisfying and easy to use click. I have to mention however that if you play on very low sensitivity and do a lot of fast sweeps / flick your mouse, then the mousewheel does actually rattle a little bit. It is not a big deal and I imagine there will not be many people who will run into this problem, especially not when used in MMO's.
Performance / Tracking
The M90 uses and Avago ADNS-9500 laser sensor. This was one of the major selling points of the mouse to me. Most MMO-mice I have seen use sensors that I have tried in the past and did not particularly like.
As expected, its tracking on my Razer Scarab hard pad was excellent in every way I could test it. The software allows you to change the lift-off distance of the mouse. I can not notice any difference between the low and medium settings. The manual indicates that results regarding lift off distance will be better on light surfaces. I can confirm that this is actually true. On the lowest lift off distance setting the sensor performed well on the Razer Scarab (the regular, light grey version), but did not track on the Steelseries Qck. Increasing lift off distance took care of the problem. The difference in lift off distance is really minimal however (we are talking about a millimeter here) and in either setting I found the lift off distance of the sensor perfectly acceptable.
When I wrote the review for the G500 I did some testing of the sensor. Since the sensor in this mouse is the same, I will assume that the same things I found then hold true now. The slight positive hardware acceleration that the sensor is rumored to have does not seem very noticeable. I have not been able to detect it on the G500 or the M90 even when playing on low sensitivity which tends to amplify acceleration issues. I checked whether the sensor held up on a steelseries QcK. No elaborate testing was necessary. While I did not notice any obvious jittering, fast movements on the steelseries QcK resulted in noticeable negative acceleration. It should be noted that those who use a higher sensitivity and do not use quick long sweeps, this problem may barely be noticeable.
The mouse boasts a 1000Hz (indicated in the software as 1 ms) polling rate and 5700 Dpi. Now those numbers sound nice, but to me increases in DPI stopped being useful after it passed 2000. I'm sure there are some who will find some use for that extremely high DPI, but most people will find it unnecessary. The high polling rate should theoretically be better, but like in the G500 I can't honestly say I notice any difference between 1000Hz and the 500Hz polling rate I am accustomed to. I end up using 500Hz anyway since I have no way of testing whether the 1000Hz polling rate is consistent.
Software
A big problem that a lot of users have complained about is the software of the mouse, that is still in beta-stage despite the mouse being out for quite a while now. I have used the beta Software version 2.12 when writing this review. So is the software as bad as people make it out to be? Well, yes and no. Yes in the sense that it is buggy and it will make you jump through a couple of hoops to make things work the way you want. No in the sense that I was able to make the profiles I wanted (Gaming, Work and general use), get the LED indicators on the mouse to indicate which one I am using, make all the function and keyboard keybinds I wanted and have the mouse run in "hardware playback" instead of software playback to avoid problems in some games. When assigned to keyboard keys, the extra buttons on the mouse worked flawlessly in the games I listed in the beginning of the review.
Here is an example of the bugginess of the software. When I went and changed lift off distance to test it for the review, the profile did not save the lift of distance when I changed it back again. To make it work, I had to change the lift of distance, then change something else as well, which somehow triggered the software to register and remember the changes I made. Here is another thing that you needed to figure out for yourself. When using the hardware playback option the mouse has 6 profiles already stored on it. The profiles you create overwrite the ones pre-stored. Making 3 profiles like I did and assigning them to LED indication "6 lights", "5 lights" and "4 lights" means that the profiles indicated by "3 lights", "2 lights" and "1 light" are the default profiles on the mouse. Got all that? No? Do not bother reading it again unless you buy the mouse. It does not surprise me that there are people who are not as willing to troubleshoot the software for a mouse. If this is you, then that is reason enough to stay away from the mouse until the software is improved and no longer in beta. If you have confidence that you are able to work your way around it, then it should not deter you from getting the mouse.
When you do get the software to work it actually is quite nice and allows for a lot of different macro's, playback options and general functions to be assigned to the buttons.
However, there was one thing missing in the software that I thought was kind of a big deal. On the G500 for example, the Logitech setpoint software allows you to use the buttons as if it were keyboard keys. Holding down the button (for example to sprint) functions similarly to pushing the key assigned to sprint on the keyboard, where you would sprint for as long as you pushed down the button. Despite the various playback options, this simple feature appeared not to be in the Corsair software. Therefore, it is not easy to bind things like sprint or "push to talk" to the buttons on the mouse. This was not a big deal for me, but people who like binding Shift or Alt modifiers to the mouse for example should be aware that this feature is currently not available on the M90 and in all honesty, it should be.
EDIT: With the release of the software update in July, a lot of the previous issues have been addressed. I did not run into bugs with the newer version of the software, and they have finally added a much needed "keystroke" option. This allows you to make the keys on the mouse function as a keyboard keystroke. Meaning that it will mimic a keypress when you press it, and hold that keypress when you hold it. It is now possible to use the buttons on the mouse to sprint / push to talk, and any other function that requires you to hold a key. Pressing, holding, and letting go will be similar to a normal keyboard key.
Conclusion
While the review sounded a little negative, I actually like the M90 a lot. In the review, I am just being real about the kind of things people may not like about the mouse. It should be noted however that I have never used a perfect mouse and for any mouse I ever used (even the ones I loved) I have plenty of things to say about them that I did not like. The important thing for me is that I like the sensor of the mouse, I like the overall shape and feel even though it forced me to change grips a little. I love the scroll wheel on it as it feels weighted and heavy and the overall feel is solid. I find the extra buttons to be usable if you have a large enough thumb and grip the mouse in a specific way, but do think that they require some getting used to and should be easier to press.
I can recommend the M90, but with some reservations. Potential buyers should take into account that dependent on your grip and size of your hand the extra buttons may not be comfortable to use, the mouse is very heavy and there are currently still problems with the software. This makes the mouse kind of a niche product in my eyes, great for me but I imagine not most other people. The fact that it is one of the few mice with this many buttons and a sensor that I consider decent works in its favor however. For some people who are choosing between MMO mice, but also play a lot of other games that put the quality of the sensor to the test, I imagine that would make this their 1st choice almost by default.
Let me start with the basics. I've used the M90 for about 3 months on a Razer Scarab mousepad. The games I have played most with this mouse are Battlefield 3, Tribes:Ascend, League of Legends, Starcraft 2, Torchlight and the Guild Wars 2 Beta. I've used several other "gaming mice" I can use for comparison. Most notably the logitech G5, logitech G500 and a Razer deathadder V1&V2. You can find my review of the G500 here.
Shape / Feel / Appearance
The Corsair M90 is relatively short mouse and almost a half an inch shorter than the G500. However, it is just as wide and has a relatively high "bump" at the back of the mouse where you rest your palm. Because of this shape, it seems most suitable for people that use a claw grip. This means that they have the back of the mouse touching their palm while having their fingers arched to operate the left and right mouse button. I have seen the palm grip being mentioned as a viable grip for this mouse, but for people with big or even regular sized hands I have to disagree that this is a viable grip. I have pretty large hands, and when I try to palm the mouse my middle finger extends far past the right mouse button and almost touches the mousepad. This is partly caused by the fact that the mouse is generally short, but made worse because Corsair has chosen to make the right mouse button shorter than the left mouse button. A strange choice, as usually the middle finger is longer then the index finger. Other mice that have an asymmetric design (Like the Roccat Kone for example) usually do things the other way around, with the right mouse button being the one that is longer. If your hands are sufficiently small however, you may be able to make the palm grip work since the rest of the mouse seems to facilitate the grip relatively well. It is also possible to use the fingertip grip with the mouse. However, you should take into account that the weight and the location of the buttons on the mouse are not ideal for this gripstyle.
My usual grip is somewhere in between palm and clawgrip, and I had to use a claw-grip and arch my fingers a bit more then usual for them to actually fit on the mouse. When I did, I found the shape of the mouse to be very comfortable. The shape of the large bump in the back fits nicely in my palm. The indentation on the left side is perfect for the thumb to rest in, which enables you to easily lift the mouse. On the right side of the mouse, where the pinky and ring finger rest, there is another indentation also making lifting the mouse easier.
The mouse has an aluminium uni-body design that adds quite a bit of weight to it but also gives it a really solid feel. Unlike most mice that I have tried over the last few years this mouse does not have that cheap plasticky feel, and feels good when holding it. The overall construction both looks and feels solid. Contributing to this is the rubberized coating that covers most of the mouse which feels nice and provides a good grip. On the left side where the buttons are, the the material used is a smooth plastic while the buttons themselves are a slightly rougher more grainy plastic. On the right side where the pinky and ring finger rest the material used is a rougher more textured plastic for added grip.
The mouse does not come with adjustable weight and is very heavy. It is heavier than the already heavy Logitech G500 (without weights) for example, which was up until now one of the heaviest mice I have ever used. Depending on playstyle and preference, some may find it already too heavy actually. I myself have gotten used to the weight, and since the last mouse I used was also very heavy the transition to this mouse was not such a big deal. But since I play on low sensitivity and pick up the mouse a lot, I do have to say that it is definitely noticeable and not everyone will like it.
Sidebuttons
The side-buttons are one of the major selling points of the M90 as it is marketed as an "MMO/RTS Mouse" due to the large number of buttons that are available. One thing i should note before I get into the use and feel of these buttons is that I have allowed myself to adjust and get used to them before the review. To familiarize myself with them they were used in games as keybinds, used for work as various macros, but also outside of games and work with functions like cut, copy, paste, find, forward and backward assigned to them.
I feel like the location of the side-buttons on the m90 are really hit or miss depending on the size of your hands and the grip you use to hold the mouse. You could argue that this is true for any mouse, but it holds especially true for the M90. With my relatively large hands in a claw grip where I have my entire thumb in the "thumb-groove" on the left side of the mouse, I found the locations of some of the side buttons uncomfortable, while others were easily in reach without having to bend my fingers into uncomfortable positions. In this regard the mouse is similar to my experience with other MMO mice with this many buttons.
The two buttons that are furthest back (closest to my palm) I find almost impossible to use in any high-pace game. The two buttons near the bottom (closest to the base plate of the mouse) are well within reach, but the problem here is that they are hard to push. You really need to apply quite a lot of force, and annoyingly, quite a lot of force under the correct angle to use them. Pushing them seems easiest by applying force horizontally from the side rather than vertically, which is odd since they seem designed to be pushed by moving the thumb downward from its resting position. Instead, they are far more easy to use by lifting the thumb and pressing them sideways.
With the exception of the most forward placed button (closest to the tip of the index finger), which required me to change the way I hold the mouse to use it, I found the remaining buttons on the side of the mouse actually quite comfortable to use. After I got used to them, I could use them without problem even in more fast paced games. For example in battlefield 3, melee, Gadget 1 and gadget 2 (for example, medkit and revive) were bound to some of these side buttons and worked well. I'm no pro, but hold a 500+ SPM and 1.8+ K/D ratio while playing objective based games on bigger maps. I say this to give an indication that I do actually require the mouse to work well, and while I just play for kicks, I play "seriously" enough for a button that does not work well to be a serious hindrance.
That said, I felt like the buttons still needed a little more force than what I would have liked to see. The design of the buttons looks as though you should push them with different parts of the thumb by sort of leaning your thumb into them. You can forget about using them like that. With the exception of the button in the upper-right corner, I ended up using the tip of my thumb to push all of the others. Since they are not all that easy to press, it is just easier to apply the required force this way. Using the buttons like this was actually fine as using them caused me no discomfort. The buttons do not really give a loud or satisfying audible or tactile feedback. Instead of feeling a clear "click" you feel and hear a more muffled click when you press them which is something you can get used to, but did not feel immediately very satisfying and reassuring.
One thing I like about the buttons is that they are quite large. They may not be incredibly easy to press but they are very easy to find. The raised ridge that is on the buttons helped in distinguishing them from each other. I also found their location on the mouse easy to remember. Another thing I did appreciate about the location of the buttons is that they do not interfere with anything when you are not using them. In the space where you would naturally rest your thumb there is an open space, allowing you to tightly grip the mouse without having to worry about the buttons. This is why I was a little surprised Corsair had chosen to make the buttons hard to press. It seems to me that having the open space for the thumb in the middle of all these buttons already takes care of the problem of accidental button presses.
All in all I thought the buttons on the side could use some improvement, but perform decently. Especially after I got used to it, I started using the buttons quickly, accurately and with confidence and stopped worrying about them being harder to push then what i am used to. With some experience and a little muscle memory you will be able to use them fine though they will never be as comfortable to me as some of the more clicky easier to use buttons found on some other mice. I do however feel like the shape size and location of the buttons compensates for this.
LMB+extra buttons / RMB
The left and right click on the mouse have a really low travel distance and require very little force to be used. When mice "click easily" it is easy for the clicking to end up feeling "loose" and unintentional, which is not the case here. I feel like the clicking here is solid. I enjoy how to combination of the weight of the mouse with the very light clicking enables me to click rapidly in FPS without going off target.
The buttons near the index finger are in a good location. I like that they have been moved as far forward as possible so that it is not necessary to arch your index finger a lot to press them. It should be noted that the software allows you to re-bind these buttons to any keypress on the keyboard, giving you the same freedom to use them as the thumb buttons. However, they require a lot of force to push and are hard to tell apart by touch, making them less than ideal to use in a game. I used them to switch between profiles that I had saved on the mouse. For this purpose they worked fine.
Scrollwheel
I really like the scroll wheel on the M90. I am quite picky with scroll wheels and it is one of the things I think Razer mice always get right. The wheel feels weighted and heavy. The scroll wheel also has a rubberized grip and is quite wide, which feels quite nice to the touch and contributes to the overall solid and grippy feel of the mouse. Clicking the wheel is easy and gives a satisfying feedback. The wheel does lie pretty deep in the mouse's body and does not stick out as much as the wheels found on some other mice. For me, this did not noticeably impact how hard or easy it was to use. It is one of the better scroll wheels I have used in mice and I like it as much as I liked the scroll-wheel on the deathadder, which is not entirely different in feel due to its width, the heavy scrolling, rubberized material and satisfying and easy to use click. I have to mention however that if you play on very low sensitivity and do a lot of fast sweeps / flick your mouse, then the mousewheel does actually rattle a little bit. It is not a big deal and I imagine there will not be many people who will run into this problem, especially not when used in MMO's.
Performance / Tracking
The M90 uses and Avago ADNS-9500 laser sensor. This was one of the major selling points of the mouse to me. Most MMO-mice I have seen use sensors that I have tried in the past and did not particularly like.
As expected, its tracking on my Razer Scarab hard pad was excellent in every way I could test it. The software allows you to change the lift-off distance of the mouse. I can not notice any difference between the low and medium settings. The manual indicates that results regarding lift off distance will be better on light surfaces. I can confirm that this is actually true. On the lowest lift off distance setting the sensor performed well on the Razer Scarab (the regular, light grey version), but did not track on the Steelseries Qck. Increasing lift off distance took care of the problem. The difference in lift off distance is really minimal however (we are talking about a millimeter here) and in either setting I found the lift off distance of the sensor perfectly acceptable.
When I wrote the review for the G500 I did some testing of the sensor. Since the sensor in this mouse is the same, I will assume that the same things I found then hold true now. The slight positive hardware acceleration that the sensor is rumored to have does not seem very noticeable. I have not been able to detect it on the G500 or the M90 even when playing on low sensitivity which tends to amplify acceleration issues. I checked whether the sensor held up on a steelseries QcK. No elaborate testing was necessary. While I did not notice any obvious jittering, fast movements on the steelseries QcK resulted in noticeable negative acceleration. It should be noted that those who use a higher sensitivity and do not use quick long sweeps, this problem may barely be noticeable.
The mouse boasts a 1000Hz (indicated in the software as 1 ms) polling rate and 5700 Dpi. Now those numbers sound nice, but to me increases in DPI stopped being useful after it passed 2000. I'm sure there are some who will find some use for that extremely high DPI, but most people will find it unnecessary. The high polling rate should theoretically be better, but like in the G500 I can't honestly say I notice any difference between 1000Hz and the 500Hz polling rate I am accustomed to. I end up using 500Hz anyway since I have no way of testing whether the 1000Hz polling rate is consistent.
Software
A big problem that a lot of users have complained about is the software of the mouse, that is still in beta-stage despite the mouse being out for quite a while now. I have used the beta Software version 2.12 when writing this review. So is the software as bad as people make it out to be? Well, yes and no. Yes in the sense that it is buggy and it will make you jump through a couple of hoops to make things work the way you want. No in the sense that I was able to make the profiles I wanted (Gaming, Work and general use), get the LED indicators on the mouse to indicate which one I am using, make all the function and keyboard keybinds I wanted and have the mouse run in "hardware playback" instead of software playback to avoid problems in some games. When assigned to keyboard keys, the extra buttons on the mouse worked flawlessly in the games I listed in the beginning of the review.
Here is an example of the bugginess of the software. When I went and changed lift off distance to test it for the review, the profile did not save the lift of distance when I changed it back again. To make it work, I had to change the lift of distance, then change something else as well, which somehow triggered the software to register and remember the changes I made. Here is another thing that you needed to figure out for yourself. When using the hardware playback option the mouse has 6 profiles already stored on it. The profiles you create overwrite the ones pre-stored. Making 3 profiles like I did and assigning them to LED indication "6 lights", "5 lights" and "4 lights" means that the profiles indicated by "3 lights", "2 lights" and "1 light" are the default profiles on the mouse. Got all that? No? Do not bother reading it again unless you buy the mouse. It does not surprise me that there are people who are not as willing to troubleshoot the software for a mouse. If this is you, then that is reason enough to stay away from the mouse until the software is improved and no longer in beta. If you have confidence that you are able to work your way around it, then it should not deter you from getting the mouse.
When you do get the software to work it actually is quite nice and allows for a lot of different macro's, playback options and general functions to be assigned to the buttons.
However, there was one thing missing in the software that I thought was kind of a big deal. On the G500 for example, the Logitech setpoint software allows you to use the buttons as if it were keyboard keys. Holding down the button (for example to sprint) functions similarly to pushing the key assigned to sprint on the keyboard, where you would sprint for as long as you pushed down the button. Despite the various playback options, this simple feature appeared not to be in the Corsair software. Therefore, it is not easy to bind things like sprint or "push to talk" to the buttons on the mouse. This was not a big deal for me, but people who like binding Shift or Alt modifiers to the mouse for example should be aware that this feature is currently not available on the M90 and in all honesty, it should be.
EDIT: With the release of the software update in July, a lot of the previous issues have been addressed. I did not run into bugs with the newer version of the software, and they have finally added a much needed "keystroke" option. This allows you to make the keys on the mouse function as a keyboard keystroke. Meaning that it will mimic a keypress when you press it, and hold that keypress when you hold it. It is now possible to use the buttons on the mouse to sprint / push to talk, and any other function that requires you to hold a key. Pressing, holding, and letting go will be similar to a normal keyboard key.
Conclusion
While the review sounded a little negative, I actually like the M90 a lot. In the review, I am just being real about the kind of things people may not like about the mouse. It should be noted however that I have never used a perfect mouse and for any mouse I ever used (even the ones I loved) I have plenty of things to say about them that I did not like. The important thing for me is that I like the sensor of the mouse, I like the overall shape and feel even though it forced me to change grips a little. I love the scroll wheel on it as it feels weighted and heavy and the overall feel is solid. I find the extra buttons to be usable if you have a large enough thumb and grip the mouse in a specific way, but do think that they require some getting used to and should be easier to press.
I can recommend the M90, but with some reservations. Potential buyers should take into account that dependent on your grip and size of your hand the extra buttons may not be comfortable to use, the mouse is very heavy and there are currently still problems with the software. This makes the mouse kind of a niche product in my eyes, great for me but I imagine not most other people. The fact that it is one of the few mice with this many buttons and a sensor that I consider decent works in its favor however. For some people who are choosing between MMO mice, but also play a lot of other games that put the quality of the sensor to the test, I imagine that would make this their 1st choice almost by default.
